Aircraft and power plant turbines operate under very harsh conditions and are subjected to extremely high stresses.
A team of scientists has developed a ceramic coating capable of sealing certain microcracks when it heats up. The idea is simple: use the temperature normally responsible for wear to trigger partial repair of the material.
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The coating contains cobalt and chromium oxides, among other substances. At high temperatures, some of these elements slowly migrate toward damaged areas. They can then fill small cracks before they grow larger.
This repair occurs without a sensor or external intervention. However, it is not instantaneous and does not restore a severely damaged part to like-new condition. The mechanism mainly acts on small defects that gradually appear during use.
The researchers tested several compositions exposed to high temperatures and friction. Formulations containing cobalt resisted cracking and wear better than those based solely on chromium oxide.
The tests were conducted at 600°C and 800°C, temperatures representative of certain hot industrial environments. At 800°C, the coating without cobalt could crack and locally lose material. Adding cobalt significantly improved its durability.
This behavior could be of interest for turbines, where a crack in a protective coating can eventually expose the component beneath it. If this damage progresses more slowly, some parts could remain in service longer before maintenance is required.
For now, the technology has been tested on material samples, not on a complete turbine in operation. The next steps will need to determine whether this self-healing capability remains effective after numerous heating, cooling, and friction cycles.